Powder dispenser and canister



Sept. 1, 1970 B. H. JOHNSTON 3,526,341

POWDER.DISPENSER AND CANISTER Filed Sept. 20, 1967 2 Sheets-Sheet 1 1 N VEN TOR. 45M4N H (/OH/VETOA/ y ATTORNEYS B. H. JOHNSTON POWDER DISPENSER AND CANISTER Sept. 1, 1970 2 Sheets-Sheet 2 Filed Sept. 20, 1967 INVENTOR ,2 6%,,- ATTORNEYS United States Patent 3,526,341 POWDER DISPENSER AND CANISTER Bevan H. Johnston, La Mesa, Calif., assignor to Stromberg-Carlson Corporation, Rochester, N.Y., a corporation of Delaware Filed Sept. 20, 1967, Ser. No. 669,097 Int. Cl. Gtllf 13/00 US. Cl. 222167 7 Claims ABSTRACT OF THE DISCLOSURE Apparatus is described for dispensing very fine powder, such as toner for an electrostatic printer. The apparatus utilizes a powder canister removably held in a rotary support. The rotary support rotates the canister to cause powder to pass out of the canister through apertures at one end.

This invention relates to dispensing apparatus and, more particularly, to improved apparatus for dispensing very fine powder, such as toner for an electrostatic printer.

In certain types of machines, it is necessary to dispense regulated amounts of very fine powder from a storage reservoir to a station at which the powder is used\in the machine. The handling of very fine powders is difficult because turbulence in the powder frequently generates a cloud causing powder to settle on surrounding machinery or operators. Turbulence may be necessary, however, since very fine powder must usually be stirred and agitated constantly in order to keep it moving. Forcing the powder, such as by a closed piston-like device, may cause the powder to pack into a solid mass.

One example of a type of machine in which very fine powder is utilized is the electrostatic printer. A latent image defined by an electrostatic charge on a sheet may be developed by spreading a very fine pigmented plastic powder, known as toner, over the surface of the sheet. The toner is electrically charged to adhere to the sheet in accordance with the latent image thereon. The excess powder is then removed from the sheet and the powder remaining on the sheet is heated to a point where it fuses to itself and to the sheet, becoming in appearance much like ink. In an electrostatic printer, dispensing apparatus may be utilized to dispense regulated amounts of toner from a storage reservoir to the device of the printer which spreads the toner on the sheet.

Because, as previously set forth, fine powder, such as toner, is diflicult to handle, some problems may be encountered in the design of satisfactory dispensing apparatus. The fine powder in the storage reservoir may occasionally require replenishment. If the reservoir is filled by pouring or spooning the powder out of a container, a cloud of powder may be generated which splashes powder on the surrounding machinery and its operators. This can be excessively messy, and in many instances have a detrimental effect on the operation of the machinery and its porduct. Because many very fine powders pack easily into a solid mass, it is usually unsatisfactory to force the powder along its path of movement. As a result the maintenance of an accurately regulated flow of fine powder may be difficult to achieve. Where the powder is gravity fed from a hopper type device, the flow of the powder out of the device is frequently dependent upon the level of powder in the hopper. This may cause an undesirable variation in dispensing rates. Additionally, it is sometimes difiicult to determine how much powder is remaining in a reservoir out of which it is being fed without taking off a cap or similar closure for the reservoir and subjecting the surrounding machinery and operators to a possible powder cloud problem.

It is an object of this invention to provide improved apparatus for dispensing very fine powder such as toner for an electorstatic printer.

A further object of the invention is to provide dispenser apparatus for very fine powder wherein the powder is handled easily and in a manner which minimizes the danger of powder splashing on surrounding objects or operators.

Still another object of the invention is to provide dispensing apparatus for very fine powders wherein a steady regulated output is provided which is not afiected by the level of the powder in the reservoir.

A still further object of the invention is to provide dispensing apparatus for very fine powders wherein a ready indicia of powder level is provided.

Other objects of the invention will become apparent to those skilled in the art from the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a schematic diagram illustrating an electrostatic printer which may utilize a toner dispenser con structed in accordance with the invention, the latter being indicated in dotted lines;

FIG. 2 is a side view, partially in section, and with parts broken away, of a toner dispenser constructed in accordance with the invention and illustrating a toner canister and retainer therefor in exploded relation;

FIG. 3 is a sectional view of the dispenser taken along the line 33 of FIG. 2; and

FIG. 4 is a full section view of the canister assembly rotated about from the position shown in FIG. 2.

Very generally, the apparatus 10 of the invention includes means 11 and 12 (FIG. 3) for transporting powder from an intermediate station 13 to a dispensing station 14, and means for depositing powder at the intermediate-station from a canister. The depositing means (FIG. 2) comprise a holder 16 for removably receiving and supporting a canister 17 which contains powder and which has at least one opening 18 through which powder may pass when the canister is rotated. The holder is supported for rotation with respect to the transporting means and positions the canister so that the canister opening is adjacent the intermediate station when the canister is received in the holder. The holder is rotated to deposit powder from the canister at the intermediate station.

The invention utilizes an improved storage reservoir or canister for use with fine powder dispensing apparatus. The canister 17 (FIG. 4) comprises a body portion 19 including a wall 21 having a plurality of apertures 18 therein. A cap 22 is provided over the Wall and has a plurality of apertures 23 therein corresponding in distribution to the apertures 18 in the wall 21. The cap may be rotated with respect to the wall to operate as a shutter for aligning or misaligning the apertures and includes means 24 for mating in the rotary holder 16 of the dispensing apparatus to remain in fixed relation thereto. The wall 21 is fixed to the rest of the body portion 19 to be rotatable therewith so that relative rotation between the wall and the cap 22 may be effected by rotating the rest of the body portion with respect to the cap. This enables the shutters to be opened or closed a desired amount.

Referring now more particularly to FIG. 1, an electrostatic printer in which the invention is used is illustrated schematically. Paper coated with photo-resistive material upon which the printing is to be made is passed along a path represented by the line 26 in the direction indicated by the arrowhead, by using a suitable conveyor, not shown. The paper is charged to the required potential by means not illustrated. The paper is then carried into alignment with an image projector 27 and an image of the desired material to be printed is flashed on the surface of the charged paper. In accordance with known principles, the

impingement of light on the surface of a charged sheet of paper causes dissipation of the charge in general proportion to the amount of light striking the surface of the paper. Thus, dark areas in the flashed image will be represented by a stronger charge on the surface of the paper than light areas. A latent image is therefore formed on the surface of the paper corresponding to the strength of the static charge remaining thereon after the image flash.

After formation of a latent image on the charged paper, the paper passes into the developer 28. The developer is supplied with toner from the toner dispenser 10, which will be described in greater detail subsequently. The developer includes a rotary agitator 29 and a magnetized rotary brush 31. The brush 31 operates to uniformly spread a very fine powder or toner on the charged surface of the paper sheet. The toner may be charged oppositely from the electrostatic charged image and clings to the charged areas generally in proportion to the amount of charge thereon. To insure that the toner does not cling to the uncharged areas On the sheet, a background charge grid 32 may be provided. A suitable blower or brushing device, not illustrated, may be provided to brush off the excess toner including that which does not cling to charged areas on the paper. The latent image on the paper is thus developed, being defined by the dispersion of the toner remaining on the paper.

The developer 28 includes a trough 33 in which the toner dispenser deposits the toner. The trough also contains iron particles. Rotary action of the agitator 29 thoroughly mixes the toner and iron particles, and the iron and toner particles are triboelectrically charged to opposite polarities. The toner particles then cling to the iron particles. Rotary action of the cylinder 31, which is magnetized, picks up the iron particles and forms a brush, which is lightly stroked across the surface of the paper and develops the latent image as described above.

To fix the toner onto the sheet, the sheet is passed through a heater 34. The toner comprises in part a suitable resin which causes the pigment to fuse to itself and to the paper. The result is similar to ink on a printed page. After passing through the heater, the paper may be fed to a suitable output facility, not shown.

As previously mentioned, very fine powder, such as the toner which is utilized in the electrostatic printer of FIG. 1, is very difficult to handle. This is because the clouds of powder are easily produced, causing settling of powder on adjacent items and persons. Additionally, the fine powder of the toner is readily compacted into a solid mass, and thereby must be kept stirred and agitated in order to keep it moving. Moreover, the flow characteristics of such fine powders add complications to design of equipment in attaining a uniform steady flow of such powder.

FIGS. 2 through 4 illustrate the toner dispenser 10 used to supply toner to the developer 28 of FIG. 1. The toner dispenser includes a cast housing 36 which has a lower portion 37 defining a generally rectangular chamber 38 and which has an upper portion 39 defining a cylindrical chamber 41 having sections of different diameters. The axis of the cylindrical chamber in the upper section of the housing is inclined at an angle of approximately from the horizontal. A projection 42 on one side of the lower section of the housing provides means by which the toner dispenser may be mounted in the electrostatic printer. As will be explained, the toner is supplied to the developer through an opening in the developer housing (not shown). The opening is in the end of the trough 33 above the level of the iron-toner mixture therein and its location is indicated at 43 in FIG. 1. The powder passing therethrough falls into the mixture in the trough.

Power for operation of the toner dispenser 10 is provided by a motor 44 mounted in the rectangular chamber 38 defined by the lower section 37 of the housing 36. The motor 44 is bolted on a motor mounting plate 46. The two side edges of the motor mounting plate extend into vertical slots 47 and 48 formed in opposite vertical interior surfaces of the lower chamber 38. The upper edge of the motor mounting plate has a projection 49 thereon which extends into a corresponding recess in the upper wall of the lower chamber 38 and which is bolted to a vertical surface of the recess. The lower edge of the motor mounting plate fits against the floor of the lower chamber and is bolted to the end of a rib 51. The rib 51 projects upwardly along the floor of the chamber and extends about three-quarters of the distance across the chamber from a side wall of the lower section, as may be seen best in FIG. 3.

The motor 44 drives a gear train which transfers torque from the motor to various elements of the dispenser subsequently described. A central opening 52 is provided in the motor mounting plate and a drive shaft 53 extends from the motor through this opening. A drive gear 54 is mounted on the drive shaft and is drivingly coupled thereto by a drive pin 56. The drive gear is in engagement with a driven gear 57 which is drivingly secured to a worm shaft 58 by a drive pin 59.

The worm shaft 58 rotates a worm coil 11 for directing the toner to the developer 28 as explained below. The worm shaft extends through the driven gear and one of its ends is journalled in a bushing 61. The bushing 61 abuts the gear 57 and is supported in a recess formed in a housing cover 62. The housing cover 62 is bolted to the rest of the lower section 37 of the housing 36 to close the lower chamber 38. The worm shaft 58 has an annular member 63 which is fixed to and surrounds the shaft, and which is located on the opposite side of the gear 57 from the bushing. A flange 64 extends outwardly of the member 63 and a bearing 66 is positioned between the flange and a snap ring 67 secured to the shaft 58. A worm tube passage 68 is formed in the lower portion of the housing and a worm tube 12 is disposed in the passage. The end of the worm tube 12 has a larger diameter portion 71 which mates in a corresponding enlarged portion 72 of the passage 68. The bearing 66 permits the worm shaft to rotate with respect to the worm tube in response to the rotation of the driven gear.

The worm tube 12 projects beyond the housing and extends into the opening 43 in the trough 33 (FIG. 1). The worm coil 11 is supported on the annular member 63 and is rotated therewith by the worm shaft. The worm coil may be attached to the member 63 such as by soldering. The outer diameter of the worm coil is slightly less than the inner diameter of the worm tube and, as the worm coil is rotated, it transports or pushes toner along the tube, carrying it from the intermediate station 13 to the dispensing station 14 which is at the opening 43 (FIG. 1) in the trough 33 of the developer 28. The toner will therefore fall into the developer trough. The upper side of the worm tube near the end thereof toward the driven gear 57 is provided with an elongated opening 73 which is at the intermediate station 13 and through which the worm tube receives toner. The opening 73 communicates with the upper chamber 41 through a passage 74 provided in the housing and communicating between the upper chamber and the worm tube opening 73.

As mentioned before, the upper chamber 41 is cylindrical and of stepped diameters. The smaller end of the chamber 41 contains a shaft assembly 76 for rotating the canister holder 16', described in greater detail below. The shaft assembly 76 includes a shaft housing 77 having an outwardly turned flange 78 at one end which is bolted against a face 79 between two of the stepped diameter portions of the chamber. The shaft housing extends from the flange and terminates at the small end of the upper chamber. A shaft seal 82 is positioned between the shaft housing and a holder drive shaft 81 at the flanged end of the shaft housing. A coil spring 83 surrounds the holder drive shaft and biases a Washer 84 which surrounds the shaft in a direction away from the seal 82. A pair of bearings 86, separated by a spacer 87, also surround the shaft. One of the bearings abuts the spring-biased washer 84, whereas the other bearing is held in fixed position on the shaft by means of a pair of retaining rings 88. A further retaining ring 89 is disposed in an annular recess in the shaft housing at the opposite end from the flange 78 and engages one of the bearings to retain the bearing arrangement against the bias of the spring.

A plug button 91 is held in place by resilient projections 92 which extend into the annular space 93 between the upper section 39 of the housing and the shaft housing 77 contained therein. The plug button serves to close off the smaller end of the upper chamber 41.

The holder drive shaft 81 supports the canister holder 16 for rotation. The canister holder is of generally frustoconical configuration, having a disc portion 94 partially closing the smaller end. The disc portion is bolted to a disc 96 fixed on the holder drive shaft. A plurality of openings 97 are distributed about the frustoconical holder 16 and permit toner to pass therethrough into the upper chamber 41. The toner falls from the upper chamber through the passage 74 and the slot 73 into the worm tube 12.

Motive power for rotating the holder drive shaft 81 and canister holder 16 is taken off the worm coil 11 by means of a sprocket 98. The sprocket is mounted on the holder drive shaft 81 between the disc portion 94 of the holder and the disc 96 on the shaft. The teeth of the sprocket engage the worm coil through the passage 74 and the slot 73 and, since the worm coil and worm shaft are being positively driven by the motor, the sprocket will turn therewith to turn the holder drive shaft and the canister holder.

As previously mentioned, the nature of very fine powders and, in particular, toner for electrostatic printers, is such as to require constant agitation in order to effect a smooth and steady flow. In order to maintain agitation of the toner in the upper chamber, an agitator is provided. The agitator consists of a disc-like portion 95 mounted on the holder drive shaft between the canister holder and the sprocket, and a plurality of agitator blades 100 which extend from the disc-like portion. The agitator blades are twisted slightly and terminate close to the walls of the upper chamber in order to scrape any powder which may adhere to the Walls. The agitator rotates with the holder drive shaft and the canister holder and sprocket.

The construction of the toner dispenser thus far described effects a smooth and continuous flow of toner passing through the openings in the canister holder, through the worm tube to the developer. The rotary holder permits a powder containing canister to be inserted therein, and rotates the canister such that toner will fall therefrom through the openings in the canister holder. Upon depletion of the toner in the canister, the open construction of the canister holder permits ready replacement of the empty canister with a full one.

The canister 17, which may be used in the previously described dispenser, is illustrated in FIGS. 2 and 4. The canister includes a body or jar 19, preferably made of some clear substance such as polystyrene in order that the level of toner therein may be readily observed by an operator. The jar is generally cylindrical in shape, but has a slight taper along its axis to facilitate emptying of the jar. One end of the jar is closed by a wall 99 which may be molded integral with the rest of the jar. A projection 101 is provided in the wall 99 and has a conical notch 102 therein. This notch accommodates a V-shaped projection 103 in a generally U-shaped spring retainer 104. The two ends 106 (only one of which is visible in the drawings) of the retainer fit into two holes 107 (only one of which is visible in the drawings) on opposite sides of the upper portion 39 of the housing 36, permitting the jar to rotate with respect to the housing, but holding it in the rotating holder, as will be explained in more detail below.

The end of the jar 19 opposite the wall 99 is closed by the front end wall 21. The front end wall has a discshaped portion 108 and a frustoconical portion 109 joining the disc-shaped portion to the forward edge of the jar. The front end wall may be attached to the edge of the jar by suitable means such as threads, a snap, or glue. In any case, such attachment should fix the front end wall 21 to the rest of the jar 19 so that the front end wall will turn with the jar.

The frustoconical portion 109 of the front end wall 21 is provided with the plurality of apertures 18 distributed thereabout. The apertures 18 are distributed in identical manner to the distribution of openings 97 around the frustoconical holder 16. Accordingly, the apertures 18 in the front end wall 21 of the canister 17 may be aligned with the openings 97 in the holder 16 to permit toner to pass out of the canister and into the upper chamber 41 in the upper portion 39 of the housing 36.

In handling toner and other fine powders, as mentioned before, clouds of the toner may be produced relatively easily. It is therefore desirable that the canister 17 be kept closed until the last possible moment before use. The canister 17 may be kept closed until actually positioned for operation in the dispenser 10, and particularly, until received in the holder 16. Possibility of splashing of powder on surrounding equipment and operators is thereby eliminated.

-To effect closure of the canister until it is positioned for operation, the closure cap 22 is secured over the front end wall 21. The closure cap conforms in shape to that of the front end wall and the holder 16, and includes a disc portion 111, and a frustoconical portion 112 extending outwardly thereof. The outer periphery of the frustoconical portion of the closure cap includes a ring extension 113 with an inwardly turned lip 114. This lip snaps over the periphery of the end wall 21, engaging an outwardly turned flange 116 on the jar 19. This secures the closure cap in place, but permits the closure cap 22 to turn with respect to the front end wall 21. The closure cap is provided with the plurality of apertures 23 distributed around the frustoconical portion thereof in the same pattern as the apertures 18 in the end wall 21 and the openings 97 in the holder 16. Accordingly, the closure cap acts as a shutter for opening and closing the apertures in the end wall.

With the apertures 23 in the closure cap 22 misaligned with the apertures 18 in the end wall 21 to an extent such that there is no overlap, the canister 17 is completely closed and powder cannot escape therefrom. After the canister is inserted in the holder 16, the operator may grip the jar 19 and turn it to cause relative rotation between the closure cap and the end wall and thus bring the two sets of apertures therein into a desired degree of alignment. By regulating the degree of alignment, the flow of powder from the canister may be regulated.

In order for powder to flow from the canister through the openings in the holder, it is, of course, necessary that the apertures in the closure cap be aligned with the openings in the end wall. To accomplish this alignment, the end cap is provided with the elongated ridge or projection 24 extending outwardly from the disc portion thereof. A corresponding recess 116 is provided in the holder 16 and, when the canister 17 is placed in the holder, the elongated projection mates in the recess and prevents the closure cap from turning with respect to the holder. The orientation of the projection and the recess is such that the apertures in the end cap are aligned with the openings in the holder. With the apertures in the end wall misaligned, however, powder will not flow out of the canister as explained above. It is thereby necessary for the operator to turn the jar to bring the apertures in the end wall into at least partial alignment with the apertures in the closure cap. This done, the motor may be started and the dispenser operated.

The canister may be constructed of low cost plastic, such as polystyrene, such that it may be disposed of when empty. Messy refilling operations thereby are unnecessary, as the canisters may be filled directly at the suppliers factory and the user need not expose himself to the undesirable task of handling toner in an open environment. The canisters, however, may be constructed to be refillable if desired, since the canisters may be filled either through the apertures in the end wall and closure cap, or may be filled by removing the closure cap and end wall therefrom. 'It has been found that this type of canister construction, when utilized in accordance with the dispenser of the invention, effects a smooth and continuous regulated flow of toner to the developer. Clogging and packing of the powder is avoided and, as previously mentioned, there is no possibility of clouding or splashing of toner since the canisters remain unopened until positioned for operation.

It may therefore be seen that the invention provides improved apparatus for dispensing very fine powders, such as toner for an electrosatic printer. The dispensing apparatus of the invention is such that handling of the powder is easily accomplished, an indication of powder level is readily available since the jar may be transparent, and a steady output of powder is provided which is not alfected 'by the level of the powder in the reservoir.

Various embodiments of the invention in addition to those shown and described herein will be apparent to persons skilled in the art from the foregoing description and accompanying drawings. Such other embodiments, and modifications thereof, are intended to fall within the scope of the appended claims.

What is claimed is:

1. Apparatus for dispensing very fine powder, including in combination, a housing, means for transporting powder from an intermediate station to a dispensing station, a holder for removably receiving a powder containing canister which has at least one opening therein for passing powder out of the canister when the canister is rotated, said holder comprising a receptacle adapted to mate with at least a portion of the canister, said receptacle being apertured to permit powder from the canister to flow therethrough, means supporting said holder for rotation with respect to said housing and being positioned to support said holder so that the canister opening is adjacent said intermediate station when the canister is received in said holder, and means for rotating said holder to deposit powder from the canister at the intermediate station.

2. Apparatus according to claim 1 wherein said receptacle includes means for holding a canister received therein in a fixed relationship with said receptacle.

3. Apparatus according to claim 2 including a powdercontaining canister having one end with at least one opening therein, said one. end being disposed in said receptacle and being positioned by said holding means with said opening substantially aligned with an aperture in said receptacle to permit powder to flow therethrough.

4. Apparatus according to claim 3- wherein said one end of said canister has means thereon for closing said opening therein to prevent escape of powder when said canister is not received in said receptacle.

5. Apparatus according to claim 4 wherein said closing means are operable to open said openings with said canister received in said receptacle.

6. Apparatus according to claim 4 wherein said one end of said canister comprises a wall having a plurality of first apertures therein, wherein said closing means comprise a cap having a plurality of second apertures therein corresponding in pattern to said first apertures, said cap being rotatable with respect to said wall to operate as a shutter for aligning or misaligning said first and second apertures.

7. Apparatus according to claim 6, wherein said cap mates in said receptacle in fixed relation thereto with said second apertures in said cap aligned with the apertures in said receptacle, and wherein said wall is fixed to the rest of said canister to be rotatable therewith, whereby relative rotation between said wall and said cap may be effected by rotating the rest of said canister with respect to said holder.

References Cited UNITED STATES PATENTS 426,993 4/ 1890 Goldsmith 222--167 1,068,340 7/1913 Hennessee 222-168 1,539,123 5/1925 Lehman 209-650 3,319,825 5/1967 Dore 222169 X 3,339,807 9/1967 Eichorn 222-471 ROBERT B. REEVES, Primary Examiner F. R. HANDREN, Assistant Examiner US. Cl. X.R. 222-325, 333

UNITED STATES PATENT] OFFICE CERTIFICATE OF CORRECTION Patent No. 3 526, 34]. Dated September 1., 1970 I v t fl Bevan H. Johnston It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, lines 3 and 4 instead of "assignor to Stromberg-Carlson SIGNED AM 97 .329

(SEAL) Mama-.1:-

FORM PO-105O (10-69) USCOMM DC 60376d=9 in us, GOVIINIIINT ulu'rmc orrlc: 1 "n O-Jii-SSI 

